CVE-2026-98951: riscv: ptrace: Zero-initialize regset buffers before copyin

CVE-2026-98951: riscv: ptrace: Zero-initialize regset buffers before copyin

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

riscv: ptrace: Zero-initialize regset buffers before copyin

user_regset_copyin() only copies `count` bytes, so a PTRACE_SETREGSET
request with a short iov_len leaves the rest of the stack buffer
uninitialized. In riscv_vr_set() that garbage is validated and copied
into the target's vstate, and in riscv_cfi_set() it can be stored as
the target's shadow stack pointer. Zero both buffers, as the get path
already does.

The Linux kernel CVE team has assigned CVE-2026-98951 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.6 with commit 9300f00439743c4a34d735e1a27118eb68a1504e and fixed in 7.2.11 with commit 89fc70d73f4ac8781f9e15edd1dbc6b6088453b3
	Issue introduced in 6.6 with commit 9300f00439743c4a34d735e1a27118eb68a1504e and fixed in 7.3 with commit 59052a88ba5fe4a7bb34b3a0a42aa5d453d3bb97
	Issue introduced in 6.5.3 with commit f2a9cd050901c4734bc175294c3bd6a40a1a9e99

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-98951
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	arch/riscv/kernel/ptrace.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/89fc70d73f4ac8781f9e15edd1dbc6b6088453b3
	https://git.kernel.org/stable/c/59052a88ba5fe4a7bb34b3a0a42aa5d453d3bb97